1. Field of the Invention
The present invention relates to a cleaning liquid for electronic materials, particularly, silicon wafers, and to a cleaning method using the same.
2. Background Art
Currently, in manufacturing techniques of semiconductor LSIs using silicon wafers, use of large diameter wafers and further fine processing techniques are required. Furthermore, solving problems such as maintenance and improvement of product quality that comes along with complexity of processes and reduction in production cost is also required.
Particularly, in many fields of manufacturing techniques of semiconductor LSIs using silicon wafers, so-called wet treatment steps including treatment by various solutions are essential steps. A particularly important step among the wet treatment steps is a cleaning step. In conventional cleaning steps, improvements have been mainly made at the point of selection of component compositions of cleaning liquids, concentrations thereof, cleaning temperatures, cleaning time and the like (for example, “New Edition, Clean Technology of Silicon Wafer Surface” written and edited by Takeshi Hattori, Realize Co. Ltd. (2000)). However, these conventional techniques were not enough for satisfying demands caused along with recent necessity of further fine processing techniques, complexity of steps, high cleanliness, and reduction in cost. Moreover, recently, dilute chemical solution cleaning, cleaning without chemical solutions and the like are desired by demands for strict environmental protection measures and reduction in cost of waste liquid processing.
As a method for solving these problems, research and development of so-called functional water typified by “ozone water” or “hydrogen water” has been energetically carried out, and practical use thereof has been developed. Practical use of ozone water has been developed in wide fields of semiconductor cleaning in removal of metal impurity contamination and organic substance contamination. Hydrogen water is applied in glass substrate cleaning of liquid crystal displays in order to remove particles (for example, “Functional Water Leaning From the Elements” supervised by Masayuki Toda, edited by Japan Industrial Conference on Cleaning, Kogyo Chosakai Publishing Co., Ltd. (2002)).
Hydrogen water is expected to be used as a substitute for ammonia+hydrogen peroxide (hereinafter, described as “APM”) which is widely applied as a cleaning liquid for particle removal in the field of semiconductor cleaning. Hydrogen water is extremely advantageous in terms of chemical solution cost compared with APM; however, it is inferior in particle removal ability. Hydrogen water has been put into practical use since the cleaning level is enough for cleaning of glass substrates for liquid crystal displays; however, it has not been put into practical use in the field of cleaning of semiconductors such as silicon wafers since the cleaning ability is insufficient.
Therefore, the ability of hydrogen water has to be improved so as to develop APM substituting techniques which are low cost in semiconductor cleaning.